Nevertheless, I want to put forward the thesis as a strong heuristic
that language learners (implicitly) apply when learning the meaning
of a new word. The default rule that if a newly encountered word is
not a noun, then its meaning depends only on a single domain will
simplify the acquisition of the meaning for the learner (cf. Bloom 2000,
Chapter 8). In general, the syntactic markers of a word indicate its
semantic role. Thus the markers help identify the relevant domain for
the word. Lupyan and Dale (2010: 8) make “the paradoxical prediction
that morphological overspecifi cation, while clearly diffi cult for adults,
facilitates infant language acquisition.” Mandler (2004: 281) argues
along the same lines:
Many of the grammatical aspects of language seem impossibly
abstract for the very young child to master. But when the concepts
that underlie them are analyzed in terms of notions that children
have already conceptualized, not only does the linguistic problem
facing the child seem more tractable but also the types of errors
that are made become more predictable. The invention of grammatical
forms to express conceptual notions that are salient in a young
child’s conceptualization of events seems especially informative.
Since the relevant domain is often determined by the communicative
context in which the word is uttered, applying the single-domain
thesis will make the identifi cation of the new meaning much more effi -
cient. Thus I propose that a general single-domain bias provides one of
the fundamental reasons why humans can learn a language as quickly
as they do